1. Field of the Invention
The present technique relates to a recording medium having a security function and used in a photographing apparatus, for example.
2. Description of the Related Art
Conventionally, such a recording medium has been realized that can encrypt and store image data captured by a photographing apparatus. To realize encryption, an encryption key is required to encrypt plane text data. Also, a decryption key is required to decode the encrypted data. In some encryption systems, the same key is used as both the encryption key and the decryption key. One or both of the encryption key and the decryption key must be managed securely so as not to be leaked to a third party.
As means for securely keeping these key data, such an IC card is considered potent that is designed to make it difficult to decode the stored data on software and on hardware. For example, Unexamined Japanese Patent Publication No. 2001-320668 discloses a photographing apparatus which stores key data confidentially in a storage device such as an IC card, and encrypts digital data with the stored key.
Further, such a recording medium having a security function is known that makes it possible, when an authentication procedure has not been completed, to select either a mode in which the captured image data are not encrypted and stored or a mode in which the captured image data are encrypted and stored.
On the other hand, in the business-use photographing apparatus used for news reporting or the like, such an instantaneous operation is required that can start shooting immediately after power-on. However, the recording medium having a security function cannot execute the encryption-recording operation, nor confirm the recorded encrypted contents data, before completing authentication. Therefore, it was difficult for the recording medium having a security function used in the business-use photographing apparatus to balance the instantaneous operation to allow quick start of shooting after power-on with the operation to secure the confidentiality of the recorded data.